This invention relates to computed tomographic (CT) imaging, and more particularly to methods and apparatus for reducing imaging artifacts in image generated using a multi-slice CT imaging system.
Some known helical algorithms use helical weighting functions that are determined based on the geometric information of a scanner. In other words, the weighting function does not change from scan-to-scan or patient-to-patient, as long as the scanning protocol remains the same. Although these algorithms have been performing somewhat satisfactorily in a clinical setting, recent investigations have revealed severe image artifacts. Studies have shown that all of the existing algorithms perform roughly the same in terms of image artifacts. Traditionally, these artifacts are suppressed by applying a low-pass filtering along the z-axis. The low-pass filtering can be carried out either in the projection space or in the image space. This approach, however, merely trades off image artifacts with the slice thickness. In order to achieve reasonable artifact suppression, a 20% or more degradation in slice thickness is encountered.
In one aspect, a method for generating an adaptively interpolated projection of an object with an imaging system is provided. The method includes generating a first projection using a first interpolation kernel, generating a second projection using a second interpolation kernel, different from the first interpolation kernel, and taking a difference between the first projection and the second projection to generate a differential signal.
In another aspect, a computer to generate an adaptively interpolated projection of an object with a scanning imaging operable in at least one of a high speed data acquisition mode and a high quality data acquisition mode is provided. The computer is programmed to generate a first projection using a first interpolation kernel, generate a second projection using a second interpolation kernel, different from the first interpolation kernel, and take a difference between the first projection and the second projection to generate a differential signal.
In a further aspect, a computed tomographic (CT) imaging system for generating an adaptively interpolated projection of an object is provided. The CT system includes a detector array, at least one radiation source, and a computer coupled to the detector array and the radiation source. The computer is configured to generate a first projection using a first interpolation kernel, generate a second projection using a second interpolation kernel, different from the first interpolation kernel, take a difference between the first projection and the second projection to generate a differential signal, filter the differential signal using a low-pass filter, and map the filtered differential signal to a scaling function to generate an adaptively interpolated projection.